Depressive Symptoms Before, During, and After Delirium: A Literature Review

Abstract

Background: Delirium and depression are often thought of as mutually exclusive conditions. However, several studies cite depression as a risk factor for delirium whereas others note that patients with delirium often manifest depressive symptoms. Whether these depressive symptoms persist after delirium resolves remains unclear. Objectives: This article reviews published studies that have investigated the relationship between depression and delirium. Methods: Literature searches on PubMed, CINAHL, Cochrane Library, and PsycInfo were conducted using search criteria "delirium" AND "depress*" as keywords or MeSH terms. Results: Of 722 search results, 10 prospective cohort studies were identified for inclusion. These studies were categorized regarding the time of assessment for depressive symptoms. Included studies varied greatly (regarding their index population, their methods of assessment, and their timing of assessments). Of the studies, 3 involved patients undergoing hip fracture repair. They demonstrated more severe depressive symptoms both during delirium and after delirium ended. Conversely, the other studies did not find any statistically significant correlations between the 2 conditions. Conclusions: The literature suggests a correlation between depression and delirium in patients with hip fracture. Whether other specific populations have higher comorbidity is unclear. Unfortunately, studies varied widely in their methods, precluding a meta-analysis. Nonetheless, our review provides a foundation for future research.